Perioperative Syndecan-1 Dynamics During Cardiac Surgery: Associations with Operative Factors and Patient...

Background and objectives: Cardiac surgery with cardiopulmonary bypass (CPB) is associated with endothelial glycocalyx injury and perioperative endothelial dysfunction. Syndecan-1 is commonly used as a biomarker of glycocalyx shedding, but data on its perioperative changes and their relationship with operative and patient-related factors remain limited. The aim of this study was to evaluate perioperative Syndecan-1 dynamics during coronary artery bypass grafting (CABG) with CPB and to assess associations with ischemia-reperfusion exposure and patient characteristics. Materials and methods: This prospective observational study included 147 patients undergoing elective CABG with CPB. Syndecan-1 concentrations were measured at five time points: before induction of anaesthesia, immediately after aortic cross-clamp application, immediately after aortic declamping, on arrival at the ICU and 24 h after surgery. Perioperative changes were analysed using non-parametric tests, Spearman's rank correlation analysis and mixed-effects modelling. The study was registered at ClinicalTrials.gov (NCT03491163; registered on 29 March 2018). Results: Syndecan-1 concentrations changed significantly over time (p < 0.001), increasing from a baseline median of 49.74 ng/mL to a peak of 147.78 ng/mL at ICU admission, followed by a partial decline to 65.26 ng/mL at 24 h. Aortic cross-clamp duration was weakly but significantly associated with Syndecan-1 concentration at ICU admission (r_s = 0.243, p = 0.003) and with perioperative increases from baseline to ICU admission (ΔS4-1: r_s = 0.196, p = 0.017) and from aortic clamping to ICU admission (ΔS4-2: r_s = 0.207, p = 0.012). No significant associations were observed between CPB duration and Syndecan-1 concentrations in univariable analyses. In the mixed-effects model, a significant non-linear temporal pattern of Syndecan-1 concentrations was observed (both linear and quadratic time terms, p < 0.001). Male sex (β = 0.247, p = 0.009) and aortic cross-clamp duration (β = 0.016, p = 0.005) were independently associated with higher Syndecan-1 concentrations, whereas smoking status, age, BMI, diabetes status, EuroSCORE II, and CPB duration were not independently associated. Conclusions: Syndecan-1 concentrations increase significantly during cardiac surgery with cardiopulmonary bypass, peaking at ICU admission and partially declining within 24 h. Aortic cross-clamping duration, but not total CPB duration, showed weak associations with glycocalyx shedding. Male sex was independently associated with higher Syndecan-1 concentrations. These findings support ischemia-reperfusion injury as an important contributor to endothelial glycocalyx shedding during cardiac surgery.